Traditional transformers have been in use for over 100 years. They are used broadly in electronic and electrical power applications, where they are essential for the transmission, distribution and utilization of electricity. They are used to transform input power, typically accessible power at 120V AC, to a higher or lower voltage output appropriate for the use. Transformer physics shows that only input real power can be transformed to output real power with an overall efficiency of less than 100%. One type of power loss is eddy current losses (minimized by insulation). Transformers transfer energy by inductive coupling between its wound coils and circuits. One coil is the primary coil, while others are referred to as secondary. Basically a varying current passing through the primary coil creates a magnetic flux in the transformer's core which in turn produces a magnetic flux through the secondary coils. The magnetic flux in the secondary coils induces a varying and usually different electromotive force or voltage.